Add support for "dependencies" in pg_restore_extended_stats()

This commit adds support for the restore of extended statistics of the
kind "dependencies", for the following input data:
[{"attributes": [2], "dependency": 3, "degree": 1.000000},
 {"attributes": [3], "dependency": 2, "degree": 1.000000}]

This relies on the existing routines of "dependencies" to cross-check
the input data with the definition of the extended statistics objects
for the attribute numbers.  An input argument of type "pg_dependencies"
is required for this new option.

Thanks to the work done in 0e80f3f88d for the restore function and
e1405aa5e3 for the input handling of data type pg_dependencies, this
addition is straight-forward.  This will be used so as it is possible to
transfer these statistics across dumps and upgrades, removing the need
for a post-operation ANALYZE for these kinds of statistics.

Author: Corey Huinker <corey.huinker@gmail.com>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Discussion: https://postgr.es/m/CADkLM=dpz3KFnqP-dgJ-zvRvtjsa8UZv8wDAQdqho=qN3kX0Zg@mail.gmail.com

doc/src/sgml/func/func-admin.sgml

@@ -2194,9 +2194,8 @@ SELECT pg_restore_attribute_stats(
 </programlisting>
         </para>
         <para>
-         For example, to set the <structfield>n_distinct</structfield>,
+         For example, to set some values for the statistics object
-         <structfield>dependencies</structfield>, and <structfield>exprs</structfield>
+         <structname>myschema.mystatsobj</structname>:
-         values for the statistics object <structname>myschema.mystatsobj</structname>:
 <programlisting>
  SELECT pg_restore_extended_stats(
     'schemaname',            'tab_schema'::name,
@@ -2223,7 +2222,8 @@ SELECT pg_restore_attribute_stats(
          Other arguments are the names and values of statistics corresponding
          to columns in <link linkend="view-pg-stats-ext"><structname>pg_stats_ext</structname>
          </link>.
-         This function currently supports <literal>n_distinct</literal>.
+         This function currently supports <literal>n_distinct</literal> and
+         <literal>dependencies</literal>.
         </para>
         <para>
          Additionally, this function accepts argument name

src/backend/statistics/extended_stats_funcs.c

@@ -45,6 +45,7 @@ enum extended_stats_argnum
 	STATNAME_ARG,
 	INHERITED_ARG,
 	NDISTINCT_ARG,
+	DEPENDENCIES_ARG,
 	NUM_EXTENDED_STATS_ARGS,
 };
 
@@ -60,6 +61,7 @@ static struct StatsArgInfo extarginfo[] =
 	[STATNAME_ARG] = {"statistics_name", TEXTOID},
 	[INHERITED_ARG] = {"inherited", BOOLOID},
 	[NDISTINCT_ARG] = {"n_distinct", PG_NDISTINCTOID},
+	[DEPENDENCIES_ARG] = {"dependencies", PG_DEPENDENCIESOID},
 	[NUM_EXTENDED_STATS_ARGS] = {0},
 };
 
@@ -257,6 +259,7 @@ extended_statistics_update(FunctionCallInfo fcinfo)
 	 * were provided to the function.
 	 */
 	has.ndistinct = !PG_ARGISNULL(NDISTINCT_ARG);
+	has.dependencies = !PG_ARGISNULL(DEPENDENCIES_ARG);
 
 	if (RecoveryInProgress())
 	{
@@ -355,6 +358,23 @@ extended_statistics_update(FunctionCallInfo fcinfo)
 		success = false;
 	}
 
+	/*
+	 * If the object cannot support dependencies, we should not have data for
+	 * it.
+	 */
+	if (has.dependencies && !enabled.dependencies)
+	{
+		ereport(WARNING,
+				errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("cannot specify parameter \"%s\".",
+					   extarginfo[DEPENDENCIES_ARG].argname),
+				errhint("Extended statistics object \"%s\".\"%s\" does not support statistics of this type.",
+						quote_identifier(nspname),
+						quote_identifier(stxname)));
+		has.dependencies = false;
+		success = false;
+	}
+
 	/*
 	 * Populate the pg_statistic_ext_data result tuple.
 	 */
@@ -396,6 +416,24 @@ extended_statistics_update(FunctionCallInfo fcinfo)
 		statext_ndistinct_free(ndistinct);
 	}
 
+	if (has.dependencies)
+	{
+		Datum		dependencies_datum = PG_GETARG_DATUM(DEPENDENCIES_ARG);
+		bytea	   *data = DatumGetByteaPP(dependencies_datum);
+		MVDependencies *dependencies = statext_dependencies_deserialize(data);
+
+		if (statext_dependencies_validate(dependencies, &stxform->stxkeys, numexprs, WARNING))
+		{
+			values[Anum_pg_statistic_ext_data_stxddependencies - 1] = dependencies_datum;
+			nulls[Anum_pg_statistic_ext_data_stxddependencies - 1] = false;
+			replaces[Anum_pg_statistic_ext_data_stxddependencies - 1] = true;
+		}
+		else
+			success = false;
+
+		statext_dependencies_free(dependencies);
+	}
+
 	upsert_pg_statistic_ext_data(values, nulls, replaces);
 
 cleanup:

src/test/regress/expected/stats_import.out

@@ -1756,6 +1756,22 @@ HINT:  Extended statistics object "stats_import"."test_stat_dependencies" does n
  f
 (1 row)
 
+-- Incorrect extended stats kind, dependencies not supported
+SELECT pg_catalog.pg_restore_extended_stats(
+  'schemaname', 'stats_import',
+  'relname', 'test',
+  'statistics_schemaname', 'stats_import',
+  'statistics_name', 'test_stat_ndistinct',
+  'inherited', false,
+  'dependencies', '[{"attributes": [2], "dependency": 3, "degree": 1.000000},
+                    {"attributes": [3], "dependency": 2, "degree": 1.000000}]'::pg_dependencies);
+WARNING:  cannot specify parameter "dependencies".
+HINT:  Extended statistics object "stats_import"."test_stat_ndistinct" does not support statistics of this type.
+ pg_restore_extended_stats 
+---------------------------
+ f
+(1 row)
+
 -- ok: ndistinct
 SELECT pg_catalog.pg_restore_extended_stats(
   'schemaname', 'stats_import',
@@ -1769,6 +1785,35 @@ SELECT pg_catalog.pg_restore_extended_stats(
  t
 (1 row)
 
+-- dependencies value doesn't match definition
+SELECT pg_catalog.pg_restore_extended_stats(
+  'schemaname', 'stats_import',
+  'relname', 'test',
+  'statistics_schemaname', 'stats_import',
+  'statistics_name', 'test_stat_dependencies',
+  'inherited', false,
+  'dependencies', '[{"attributes": [1], "dependency": 3, "degree": 1.000000},
+                    {"attributes": [3], "dependency": 1, "degree": 1.000000}]'::pg_dependencies);
+WARNING:  could not validate "pg_dependencies" object: invalid attribute number 1 found
+ pg_restore_extended_stats 
+---------------------------
+ f
+(1 row)
+
+-- ok: dependencies
+SELECT pg_catalog.pg_restore_extended_stats(
+  'schemaname', 'stats_import',
+  'relname', 'test',
+  'statistics_schemaname', 'stats_import',
+  'statistics_name', 'test_stat_dependencies',
+  'inherited', false,
+  'dependencies', '[{"attributes": [2], "dependency": 3, "degree": 1.000000},
+                    {"attributes": [3], "dependency": 2, "degree": 1.000000}]'::pg_dependencies);
+ pg_restore_extended_stats 
+---------------------------
+ t
+(1 row)
+
 SELECT replace(e.n_distinct,   '}, ', E'},\n') AS n_distinct
 FROM pg_stats_ext AS e
 WHERE e.statistics_schemaname = 'stats_import' AND

src/test/regress/sql/stats_import.sql

@@ -1258,6 +1258,15 @@ SELECT pg_catalog.pg_restore_extended_stats(
   'statistics_name', 'test_stat_dependencies',
   'inherited', false,
   'n_distinct', '[{"attributes" : [1,3], "ndistinct" : 4}]'::pg_ndistinct);
+-- Incorrect extended stats kind, dependencies not supported
+SELECT pg_catalog.pg_restore_extended_stats(
+  'schemaname', 'stats_import',
+  'relname', 'test',
+  'statistics_schemaname', 'stats_import',
+  'statistics_name', 'test_stat_ndistinct',
+  'inherited', false,
+  'dependencies', '[{"attributes": [2], "dependency": 3, "degree": 1.000000},
+                    {"attributes": [3], "dependency": 2, "degree": 1.000000}]'::pg_dependencies);
 
 -- ok: ndistinct
 SELECT pg_catalog.pg_restore_extended_stats(
@@ -1268,6 +1277,26 @@ SELECT pg_catalog.pg_restore_extended_stats(
   'inherited', false,
   'n_distinct', '[{"attributes" : [2,3], "ndistinct" : 4}]'::pg_ndistinct);
 
+-- dependencies value doesn't match definition
+SELECT pg_catalog.pg_restore_extended_stats(
+  'schemaname', 'stats_import',
+  'relname', 'test',
+  'statistics_schemaname', 'stats_import',
+  'statistics_name', 'test_stat_dependencies',
+  'inherited', false,
+  'dependencies', '[{"attributes": [1], "dependency": 3, "degree": 1.000000},
+                    {"attributes": [3], "dependency": 1, "degree": 1.000000}]'::pg_dependencies);
+
+-- ok: dependencies
+SELECT pg_catalog.pg_restore_extended_stats(
+  'schemaname', 'stats_import',
+  'relname', 'test',
+  'statistics_schemaname', 'stats_import',
+  'statistics_name', 'test_stat_dependencies',
+  'inherited', false,
+  'dependencies', '[{"attributes": [2], "dependency": 3, "degree": 1.000000},
+                    {"attributes": [3], "dependency": 2, "degree": 1.000000}]'::pg_dependencies);
+
 SELECT replace(e.n_distinct,   '}, ', E'},\n') AS n_distinct
 FROM pg_stats_ext AS e
 WHERE e.statistics_schemaname = 'stats_import' AND